For 2011-2020 F-150/Mustang vehicles equipped with a 5.0L engine when installing a replacement secondary timing chain tensioner (6K254) or secondary timing chain guide (6K297), it is necessary to replace both components as a pair, using the latest level parts. Make sure to use secondary timing chain tensioner part number ML3Z-6K254-A and secondary timing chain guide part number ML3Z-6K297-A.
